Heat exchange unit



March 14, 1939.

C. A. LEIDIG HEAT EXCHANGE UNIT 2 Sheets-Sheet 1 Filed May 6, 1936INVENTOR ClaremeAleidig BY (Bu CZ- %EYS v Patented Mar. 14, 1939 UNITEDSTATES HEAT EXCHANGE UNIT Clarence A. Leidig, Bufialo, N. Y., assignorof forty-five per cent to Silas C. Wead, North Tonawanda, N. Y.

Application May 6, 1936, Serial No. 78,223

8 Claims.

This invention relates to a new and improved heat exchange unit andparticularly to a device for elevating the temperature of liquids bymeans of hot gases.

It has heretofore been proposed to utilize the hot gases which aredischarged from the fire box of a furnace or similar heating device andtransferred to a chimney or smoke stack by means of a conduit or flue.The present invention relates generally to such a device and involves anew and improved heat exchange unit which is mounted or positioneddirectly in the flue or stack leading from the fire box of a furnace orsimilar device.

It is an object of the invention to provide a device of this classwherein a high degree of thermal efficiency is obtained with a minimumof interference with the normal flow of spent gases in the dischargeconduit leading from the furnace.

In constructing the device of the present invention I have so arrangedthe various parts that a device very simple in construction, yet ruggedand efficient in operation, has resulted.

In the drawings, Fig. 1 is a general view of my invention showing aportion of a furnace and the flue leading therefrom in cross section andmy improved heat exchange um't position in the flue and shown in sideelevation.

Fig. 2 is a horizontal crosssectional view taken approximately on theline 2-2 of Fig. 3.

Fig. 3 is a vertical cross sectional view taken approximately on line 33of Fig. 2.

Fig. 4 is a fragmentary cross sectional view taken on the line ti ofFig. 1. and showing the iquid inlet port of the device.

Fig. 5 is a perspective view showing that end of my device at which thehot gases enter and to which I shall hereafter refer as the front end.

Fig. 6 is a detailed plan view of a flue section in partly disassembledrelation, showing the manner of engaging the flue section about thewater outlet pipe of my device.

Fig. '7 is a general side elevational view of a modified means forincorporating my improved heat exchanger in the hot gas outlet of afurnace.

In the embodiment of the invention disclosed in Figs. 1 through 6 of thedrawings, I have indicated, at it] in Fig. 1, the side wall of a furnacehaving an outlet i l leading from the fire box for the discharge of thegaseous products of combustion. The structure is provided with the usualflue l2 leading to a chimney or smoke stack, but contrary to the usualconstruction, I have provided a special flue section indicated generallyat i3 which provides novel means for positioning and incorporating myimproved heat exchange unit in the usual discharge structure of afurnace. My improved heater, in the form herein disclosed, comprises asemi-cylindrical casing member l4 which is formed with both of its endsopen and,

in the present instance, with a pair of vertically and longitudinallyextending partitions l5 and I6 which divide the interior of the casingl4 into three longitudinally extending chambers l1, I8 and i9.Positioned in the chambers l1, I8 and it are longitudinally extendingtubular members 25, 2t and 22 respectively. Each tubular member has across sectional contour which is similar to the cross sectional contourof the interior of its corresponding chamber but smaller in size, andeach of the tubular members 20, 2| and 22 is provided with a pluralityof protuberances 23, extending from its outer surfaces. When a tubularmember is inserted, endwise, in its respective chamber, itsprotuberances Z3 serve to locate the tubular member substantially in thecenter of its receiving chamber and thereby provide a space between thewalls of the tubular member and the interior of the wall of the chamber,which is substantially uniform throughout.

The front and rear ends of the device are provided with closure orheader members 24 and 25 respectively. The outer contour of the headermembers conforms to the outer contour of the semi-cylindrical casingmember and each header member is provided with openings correspondingvin size to the openings in each of the tubular members 20, 2! and 22.

Spaced about the semi-cylindrical upper portion of the header members 24and 25 and the casing i i are a plurality of lugs 26. Longitudie.

nally extending tie rods 2! engage the lugs 26 at their opposite endsand are each provided with an enlarged head portion 28 at one end and anut 29 at the other for holding the header members 2 and 25 securelyagainst the end faces of the casing member [4 and the tubular members20, 2| and 22. It will be seen that the header members 24 and 25 willtherefore close off the ends of the previously described spaces providedbetween the outer walls of the tubular members 20, 2| and 22 and theinner wall of the semi-cylindrical casing member It.

Communication between these three spaces is provided in the followingmanner. An opening 30 is formed in the partition member I6 at its:

upper front corner. A second opening 3i is provided in the partitionmember l5 at its lower rear corner. A liquid intake pipe 32, leadingfrom a cold water supply line or from the bottom of a hot water storagetank, communicates with the,

space between the tubular member 22 and the walls of the chamber I9 at apoint adjacent the rear end of the device, as shown in Figs. 1 and 2.Fig. 4 shows the intake pipe 32 as having a threaded end portion whichengages corresponding threads formed upon the interior of a boss 33provided at the bottom of the casing member M. The inner periphery ofthe pipe 32 may be threaded, as shown in Fig. 4, and provided with areducing bushing 34 for limiting the entry of liquid into the heatexchanger.

A discharge pipe 35 is secured in a boss 36 provided upon the upper sideof the casing 14 and communicates with the space between the member 20and the interior of the wall of the chamber ll at a point adjacent thefront of the device as will appear from Fig. 1. The discharge pipe mayfeed into the top of a hot water storage tank or lead directly towherever a supply of hot water is wanted.

It will now be clear that liquid introduced into the heat exchanger bymeans of the intake pipe 32 t the rear end of the device will traverselongitudinally the space between the tubular member 22- and the walls ofthe chamber H!) from right to left as seen in Figs. 1 and 2, and flowthrough the opening 36 into the space between the tubular member 21 andthe walls of the chamber 18. The liquid will then traverse this space ina direction from left to right as seen in Figs. 1 and 2, enter the spacebetween the tubular member 20 and the Walls of the chamber i? throughthe opening 3!, and flow through this space from right to left, as seenin Figs. 1 and 2 and be discharged from the device through the pipe 35.

It will be noted that the interiors of the tubular members 29, 2! and 22are in open communication with the interior of the flue section I 3 inwhich the device is adapted to be positioned. The front closure member24- is so formed that all of its parts taper away from the casing member44 in such manner as to provide substantially funnel-like or stream-lineentrances 33, 34 and 35 to the interior of the tubes 2B, 29 and 22respectively. This construction is provided to insure the entrainment ofa maximum volume of hot flue gases for passage through the tubularmembers on their way from the furnace to the chimney or stack. Thisconstruction also causes the velocity of the gases to be greater in thetubular members than elsewhere in the flue and this greater velocityassists materially in keeping the surface of the passages free from sootor other material which may tend to separate from the gases and depositthereupon.

While two vertically disposed partitions, l5, l6 have been shown, itwill be apparent that the number may be varied and, if desired, thepartitions may extend horizontally across the easing i4, one above theother.

Means have been provided in the header member 24 for rendering the uniteffective for elevating the temperature of liquids in the absence of hotgases in the flue section l3, as when the furnace I0 is inactive, orwhen such hot gases are insufficient. These means comprise a passage 40which extends through all parts of the header member 24 and is in opencommunication with a fuel gas inlet pipe 4i. Gas jets or ports 42 leadfrom the passage 40 at spaced intervals about the member 24 andterminate at the surface of the member 24 at points closely adjacent themeeting lines of the member 24 and the casing member l4 and the tubularmembers 20, 2| and 22. The gas inlet line 4i is, of course, providedwith a control valve not shown and when this valve is opened, gas willbe discharged from all of the jets 42 in a direction generally towardthe interior of the tubes 2t], 2! and 22. For the ignition of the gas sodischarged, a pilot light 43 is provided, positioned directly above ashort tubular member 44, that is provided in the upper part of the fluesection lit at a point just to the rear of the header member 24. Aportion of the gas issuing from the several jets 42 will pass throughthe tubular member 44 and be ignited by the constantly burning pilotlight 43, and then burn back into the interior of the flue section l3 toignite all of the several jets 42.

This gas burner arrangement serves the further useful purpose of burningor blasting out waste solid products of combustion which tend toaccumulate upon the outer walls of the casing l4 and the inner walls ofthe tubular members 20, 2| and 22.

To facilitate the mounting and positioning of the present device, theflue section i3 is formed by a pair of longitudinally extending sheetmetal members 45 and 46, approximately semi-circular in cross sectionand hinged at their bottom edges as at 41. The upper edges of themembers 45 and 46 are adapted to overlap for a substantial distance sothat the ultimate diameter of the assembled flue section may be readilyadapted to suit varying needs. Fig. 6, the upper edges of the sections45 and 46 are provided with U-shaped notches 48 and 49 respectively,which, when brought together about the outlet pipe 3 l, embrace the pipe3| and provide a substantial seal between the interior and exterior ofthe flue section I3 at this point. The portion 45 of the flue section 43is provided with an opening 50 for receiving the inlet pipe Inassembling the device, the opening 50 of the flue section I3 is firstplaced over the pipe 32. The casing l4 and its assembled tubular membersand header members are then secured to the upper end of the intake pipe32 and to the lower end of the outlet pipe 35 and are supported thereby,the arcuate upper surface of the casing member [4 being approximatelyconcentric with the assembled flue section l3 so that the space betweenthe upper portion of the casing I4 and the wall of the flue I3 issubstantialy uniform throughout. Further, this space is as small in sizeas is consistent with the passage of a sufficient quantity of the hotflue gas through the space to heat the upper surface of the device toapproximately the same degree as its other surfaces. In this way thereis a minimum of interference with normal passage of the hot flue gasesfor a given area of the heat exchange unit and the largest possibleuninterrupted area, that is, the space below the bottom wall of thecasing member 94, is presented. Disposition of the heat exchanger in theupper part of the flue i3 exposes it to contact with the hottest portionof the flue gases which will naturally be in the upper part of the flue.

When a limited amount of hot gas is issuing from the furnace this gaswill naturally traverse the upper portion of the conduit and passthrough and immediately about the heat exchanger. As the volume of hotgas increases more of it will pass through the uninterrupted spacebeneath the heat exchanged and will enjoy a normal uninterrupted flow.

The members 45 and 46 of the flue section 13 are then brought togetherat their upper edges to the position shown in Fig. 3 with the innerperipheries of their front and rear ends embracing the furnace outlet 5i and the flue l2 respectively, and are secured in this position by apair of circular clamping rings 4'! provided with securing screws orbolts 48. This construction renders the heat exchange unit convenientlyacnessible for cleaning, adjustment, repair, etc.

As is shown in The modification shown in Fig. 7 involves no change inthe heat exchange unit but provides a modified form of flue section I3which is of sufflciently greater diameter than the furnace outlet i iand the flue 12 to compensate for the interference with normal passageof Waste gas which is offered by the heat exchange unit. This form of myinvention will be particularly useful when the cross sectional area ofthe furnace outlet and flue, or the draft as it is called, isinsufficient to permit successful interposition of the heat exchangeunit in the manner shown in Fig. 1.

In operation the modification of Fig. 7 is similar to the modificationpreviously illustrated with the added advantage that the hottest portionof the waste gases will be trapped or momentarily deterred in itsmovement by the upwardly extending recess formed by the enlargement ofthe flue section Hi. This trapping interferes in no way with passage ofgas through the unobstructed lower portion of flue section I3 as therate of flow increases.

It is to be understood that the detailed description herein and theaccompanying drawings are merely exemplary and that the scope of thepresent invention is not limited in any way except as defined in theappended claims.

What is claimed is:

l. A heat exchange unit comprising a unitary casing member having aplurality of longitudinally extending passages formed therein and incommunication with each other, tubular members disposed in said passagesand means for spacing the walls of the tubular members from the Walls ofthe passages to provide a fluid conduit therebetween, fluid inlet andoutlet ports in communication with said fluid conduit, means at each endof said casing member for closing said fluid conduits, said closuremeans having openings leading to the interiors of said tubular membersand one of said closure members having a series of ports, and a conduitfor introducing fluid fuel into said closure member for dischargethrough said ports.

2. In combination with a furnace having a conduit for carrying off thegaseous products of combustion, a readily detachable flue sectioninterposed in said conduit, means for adjusting the diameter of saidflue section to fit said conduit, a heat exchanger having fluid passagestherein and intake and outlet pipes communicating therewith and disposedin said flue section.

3. A fluid heater comprising a circular conduit having a substantiallyhorizontal axis for conveying the gaseous products of combustion from afurnace, and a heat exchange unit positioned in the upper portion ofsaid conduit and comprising an elongated outer casing extendinglongitudinally of said conduit and having an arcuate upper surfaceconcentrically disposed with respect to the curvature of said conduit,said elongated outer casing member having an inlet port in its bottomsurface and an outlet port in its arcuate upper surface and longitudinalpartition members defining a zig-zag fluid passage in said cas- 4. Afluid heater comprising a circular conduit for conveying the gaseousproducts of combustion from a furnace and a heat exchange unitpositioned in the upper portion of said conduit and having a fluidpassage therein and inlet and outlet conduits communicating therewith,said heat exchange unit comprising an elongated outer casing extendinglongitudinally of said conduit and having an arcuate upper surface and asubstantially flat bottom surface, said arcuate upper surface beingdisposed concentrically with respect to said circular conduit and spacedinwardly therefrom.

5. A liquid heater comprising a conduitfor normally conducting a currentof a gas at elevated temperatures, a heat exchanger disposed in saidconduit and comprising a body portion having longitudinally extendingfluid passages therein, inlet and outlet ports communicating with saidfluid passages, closure means at each end of said body portion for saidfluid passages, and means on one of said closure members for introducingan auxiliary heating medium, said means being associated with theclosure member which is nearest to the entry end with respect to thenormal current of gas whereby the heat from the auxiliary means willsubstantially completely traverse said heat exchanger.

6. In combination, a horizontal conduit for carrying off the gaseousproducts of combustion from a furnace or the like, a portion of saidconduit being substantially circular and of greater cross sectional areathan the remainder thereof, and a heat exchange unit disposed in theupper part of said portion of said conduit, said heat exchange unitcomprising an elongated outer casing extending longitudinally of saidconduit and having an arcuate upper surface and a substantially flatbottom surface, said arcuate upper surface being disposed substantiallyconcentrically with respect to said circular conduit and spaced inwardlytherefrom, the uninterrupted cross-sectional area below said heatexchange unit being substantially equal to the cross-sectional area ofthe remainder of said conduit.

7. In combination with a fluid conduit, a heat exchange unit disposedtherein and comprising a casing member having a plurality of passagesextending longitudinally with respect to said conduit, tubular membersdisposed in said passages with their walls spaced therefrom to formfluid chambers extending continuously about said tubular members andsaid tubular members being in open communication at both their ends withthe fluid stream in said conduit, means forming connecting passagesbetween said longitudinally extending passages, said means beingdisposed between each adjacent pair of longitudinally extending passagesand disposed alternately at opposite ends thereof, and fluid inlet meanscommunicating with one of said longitudinally extending passages andfluid outlet means connecting with another of said longitudinallyextending passages.

8. A heat exchange unit comprising a casing member having a plurality oflongitudinally extending passages, tubular members disposed in saidpassages and means for spacing the walls of the tubular members from theWalls of the passages to provide fluid chambers extending about saidtubular passages, said tubular members being removably positioned insaid passages, closure means at each end of said casing for closing saidfluid chambers and openings in said closure means providing free fluidcommunication between the interior of the tubular members and thesurrounding atmosphere, said tubular members being retained in saidpassages by said closure members, and said passages being interconnectedfor fluid communication and having an inlet and an outlet port.

CLARENCE A. LEIDIG.

CERTIFICATE OF CORRECTION. Patent No 2,150,805. March 1h, 1959.

CLARENCE A'. LEIDIGo It is hereby certified that error.appears in theprinted speeification of the above numbered patent requiring correctionas follows: Page 1, first column, line 26, for the word "position" readpositioned; page 2, second column, line 6h, for exehangew' readexchanger; and that the said Letters Patent should be read with thisoorrection therein" that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 25th day of April, A. D. 195'9 Henry Van Arsdale(Seal) Acting Commissioner of Patents,

